Other common methods

Some other common methods you will use often are:

const hash = Poseidon.hash([x]); // takes array of Fields, returns Field
const privKey = PrivateKey.random(); // create a private key
const pubKey = PublicKey.fromPrivateKey(privKey); // derive public key
const msg = [hash];
const sig = Signature.create(privKey, msg); // sign a message
const isVerified = sig.verify(pubKey, msg); // Bool(true)

Try it out

Define a variable x for a Field with a default value set to 1:

const x = Field(1);

Declare a variable named hash and use the Poseidon hash function, which accepts an array of Fields as input and produces a single Field as its output:

const hash = Poseidon.hash([x]); // takes array of Fields, returns Field

Declare a variable privKey and generate a private key using the random method on the PrivateKey class:

const privKey = PrivateKey.random(); // create a private key

Declare a variable pubKey by deriving a public key from the private key using the fromPrivateKey method on the PublicKey class:

const pubKey = PublicKey.fromPrivateKey(privKey); // derive public key

Declare a variable named msg and set it to our calculated hash.

const msg = [hash];

Declare a variable named sig and generate a signature by signing the message with the private key.

const sig = Signature.create(privKey, msg); // sign a message

Define a variable named isVerified to validate the signature using the public key and the message.

const isVerified = sig.verify(pubKey, msg); // Bool(true)

We can log the value of the isVerified variable to check that we have successfully signed and verified the message:

Provable.log('is signature verified:', isVerified) // should be true

Now build and run the script in the terminal:

npm run build && node build/src/index.js